1. Field of the Invention
The present invention relates to novel traffic signs for providing roadside alerts, information or directions and to display matrices which may constitute the visual area of a traffic sign. Preferred embodiments relate to programmable traffic signs which can display a variety of messages or images.
2. Description of Related Art Including Information Disclosed under 37 CFR 1.97 and 37 CFR 1.98
Motorists and other road users are greeted by a variety of signs embodying a diversity of technologies, as they travel a nation's highways and byways that are intended to inform, guide, direct and warn the motorist about ambient geography, conditions, events and facilities.
In the computerized information and entertainment age of the twenty-first century, roadside driver information technology has not kept up. New young drivers, steeped in the organized visual richness of the Internet, used to streaming video on demand and instant replay scoreboards at ball games, and possibly having a GPS-assisted navigation system at their fingertips in their vehicle, are confronted on the highways with what are, in the case of official, as opposed to commercial, display structures, a confusing array of iron age signs built with rust bowl technologies. Clear, eye-catching signs benefit road users and promote traffic safety.
Some sophisticated roadside driver information technologies are employed, but only for special purposes, and they still employ rather crude display technology. An example is an interactive height-alerting device such as one located on the Hutchinson River Parkway, approaching New York City, which uses radar to read the height of each oncoming vehicle and displays a backlit text message to overheight vehicles requiring them to exit the parkway, to avoid colliding with a low bridge. Such devices are expensive and power hungry and do not solve the problem of providing a visually enhanced display suitable for general purpose roadside signage.
Otherwise, the most technologically advanced type of traffic sign commonly encountered is probably the box-like, programmable, luminescent traffic advisory displays found on highways such as I-95, which provide short messages of perhaps twelve or fifteen letters and may cycle through two or three messages. Commonly mounted on overpasses or other raised fixed structures near the roadway, such traffic advisory displays employ a matrix array of small incandescent or reflective light sources, which are selectively illuminated to provide light patterns in the shapes of individual letters, which are read against a dark background, much like LED displays. Substantial candlepower is required for daylight visibility. They are used to provide a selection of messages to road users, most commonly relating to traffic conditions, e.g. “RUSH HOUR TRAFFIC EXITS 15-9”; “ACCIDENT EXITS 13-11“FOG: REDUCE SPEED”. Displays of this type have poor resolution limited by the size of the light source required for adequate daylight visibility, are bulky and expensive to install and maintain, and require a significant power supply.
Other signs used for navigation and traffic management are nearly all passive, reflective signs, relying upon daylight or vehicle headlights for visibility. Examples are the green, or in some countries blue or yellow, background billboard-like signs used to indicate towns, cities and intersecting routes. Many of these signs employ coating materials with enhanced reflectivity, as may marker badges for named and numbered interstates, parkways, turnpikes and other trunk roads, and also some stop signs and the like. Particularly effective at night are retroreflective coatings which have significant capacity to reflect received light back to the source in a direction parallel to the incident path, giving motorists good visibility by the light from their own headlights, and perhaps occasional glare when sunlight catches the sign at just the right angle. Retroreflectivity can be provided by incorporating glass beads in the paint or other coating used to provide the sign's reflective surface, see for example U.S. Pat. No. 5,514,441 (Pohto et al.), U.S. Pat. No. 6,054,208 (Rega et al.) and U.S. Pat. No. D413,731 (Hannington), assigned to Avery Dennison Corporation; U.S. Pat. No. 3,700,305 (Bingham) and other related patents assigned to Minnesota Mining and Manufacturing Company; U.S. Pat. No. 5,936,770 (Nestegard) and other related patents assigned to 3M Innovative Properties Company.
Other signs such as state route markers, lane markers and the like, employ old fashioned black paint on a white background providing an inferior visual effect. Such signs are easily overlooked under conditions of poor visibility, or when the field of view is congested with traffic, or with other official or commercial signs, or is simply badly located.
By way of example of the drawbacks of existing sign technology, countless accidents, some of them fatal, are caused every year by the failure of motorists to observe one of the familiar octagonal red stop signs that are ubiquitous on American roads. It would be desirable to have an active sign technology which could catch the attention of unobservant drivers.
While a greater variety of commercial outdoor advertizing and promotional display devices is available, laced with eye-catching characteristics such as videotext, neon, and sometimes full-color video, none known to applicant offers a satisfactory combination of characteristics to provide an enhanced roadside visual communication technology suitable for widespread deployment. Known visually striking commercial display technologies are usually high maintenance, high cost, and insufficiently rugged and durable to be widely adopted for general purpose roadside signage.
There is accordingly a need for a display technology which can provide low-cost, low-maintenance traffic signs with enhanced visibility and eye-catching characteristics. There is a further need for such technology to be programmable to display a variety of messages or images.